How see?
See? /s
Mostly these helmets are made for jousting, so that narrow visor is all they need. Just have to see the guy right in front (and slightly to the side) of you in bright colors coming at you at a full gallop.
Still looks pretty insane. As in, the only way the top of most wearers’ heads would fit is if the eyeslit was way above the visual line, naturally giving a small view of the sky, high above.
Then to counter that, and actually see your opponent, it seems like you’d awkwardly need to tilt (NPI) the whole bloody assembly way down in to your chest. Sun also being a factor could be brutal.
Cool, looks like their head is strapped to the helmet which extends quite far down to immobilize the neck and prevent whiplash.
Edit: from the wiki:
By the late 15th century, it had become customary for this type of helmet to be mounted with screws or rivets onto the wearer’s cuirass, though this only allowed the wearer to look forward, rendering helmets worn that way only suitable for jousting charges.
